Paulomycin A and B are well-known antibiotics producible by fermentation means as disclosed in U.S. Pat. No. 4,335,108. Example 1 of the patent discloses the fermentation process and recovery of paulomycins A and B. Examples 2 and 3 disclose the isolation processes for preparing the essentially pure crystalline preparations of paulomycin A and paulomycin B, respectively. The antibiotics are characterized by physical and chemical parameters.